What are you trying to do exactly when you get the error?

when I get this error I just reinstall ALM or close the entire session and work on it, but recent times these 2 methods are not working still am getting this error . Which method is used to recover from this error

Hello Nandhini,
This is a basic generic error and not necessarily related to any specific issue. The nature of such issue could be many possibilities, Several of the options could be that the back end DB has in errant entry and the entity selected in the focus of the current display can't be resolved due the missing/errant linkage, the entity has been deleted within the repository system and wasn't cleaned up correctly by the systems clean utility and still exists in the back end errantly, the users has an errant cached reference to said entity (each users system has cached information, time retrieval exceeded a set time expectation and created an error condition. As you can see it could be any number of issues creating the issues and would require trouble shooting and analyzation of the log files to determine in this particular case the nature of the issue.

I would suggest you open a support case with your support team to find the nature of the issue. I hope this helps clarify some,
Dan